Process for producing acrylic acid or methacrylic acid

Abstract

An improvement in the process for producing acrylic or methacrylic acid by the vapor phase catalytic oxidation of a system containing acrolein or methacrolein, respectively, is provided. The improvement resides in the employment, in such process, of a novel catalyst prepared by admixing with a solution of the catalytic component an organic substance, for example from the group of organic acids, alcohols, amines and esters, drying the admixture and subsequently calcining the admixture at a temperature in the range of 330° C to 430° C to form the novel catalyst.

What is claimed is: 
     
       1. In a process for producing acrylic acid or methacrylic acid by the vapor phase catalytic air oxidation of acrolein or methacrolein, respectively, wherein the catalyst used is prepared from an admixture containing water-soluble vanadium and molybdenum compounds and an organic reducing agent having intramolecular oxygen, nitrogen or both, which organic reducing agent is at least one substance selected from the group consisting of carboxylic acids, alcohols, amines and esters and has a boiling point of 150° C. or more at the pressure utilized for calcining the catalyst and is water-soluble or forms an aquasol or an aquagel in the presence of water, the improvement wherein the admixture of molybdenum compounds, vanadium compounds and reducing agent is calcined at a temperature in the range of 330° C. to 430° C., and the amount of reducing agent is at least 5 percent by weight based on the combined weight of the molybdenum and vanadium oxides resulting from calcination. 
     
     
       2. The process according to claim 1, wherein the organic reducing agent is water-soluble and has a boiling point of at least 150° C. 
     
     
       3. The process according to claim 1, wherein the organic reducing agent forms an aquasol or aquagel in the presence of water and has a boiling point of at least 150° C. 
     
     
       4. The process according to claim 1, wherein the organic reducing agent is at least one substance selected from the group consisting of glycerol, oxalic acid, succinic acid, lactic acid, ethanol amine, diethanol amine, ethylene glycol, diethylene glycol, propylene glycol, diethylene triamine, triethylene tetramine, lauryl alcohol, dioctyl phthalate, tricresyl phosphate, hydroquinone and β-alanine. 
     
     
       5. The process according to claim 1, wherein the organic reducing agent is selected from the group consisting of oxalic acid, succinic acid, capric acid, hexanoic acid, ethylenediamine tetraacetic acid, benzoic acid, β-alanine and lactic acid. 
     
     
       6. The process according to claim 1, wherein the organic reducing agent is at least one member selected from the group consisting of lauryl alcohol, ethylene glycol, diethylene glycol, propylene glycol, glycerol and benzyl alcohol. 
     
     
       7. The process according to claim 1, wherein the organic reducing agent is at least one member selected from the group consisting of ethylenediamine, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, phenylenediamine, monoethanolamine and diethanolamine. 
     
     
       8. The process according to claim 1, wherein the organic reducing agent is selected from the group consisting of dioctyl phthalate and tricresyl phosphate. 
     
     
       9. The process according to claim 1, wherein the organic reducing agent is hydroquinone. 
     
     
       10. The process according to claim 1, wherein the water-soluble compounds are ammonium molybdate and ammonium meta-vanadate. 
     
     
       11. The process according to claim 10, wherein 5-60% by weight of glycerol is incorporated into an aqeuous solution of the compounds and the resultant mixture is dried and calcined. 
     
     
       12. The process according to claim 1, wherein acrylic acid is produced by oxidizing acrolein. 
     
     
       13. The process according to claim 1, wherein methacrylic acid is produced by oxidizing methacrolein. 
     
     
       14. The process according to claim 1, wherein the organic reducing agent is employed in an amount of at least 20% by weight of the combined weights of the molybdenum and vanadium oxides. 
     
     
       15. The process according to claim 1, wherein calcination is conducted at 370°-400° C. 
     
     
       16. The process according to claim 1, wherein fused alumina is incorporated into the admixture of the compounds. 
     
     
       17. The process according to claim 1, wherein phosphoric acid is incorporated into the admixture of the compounds. 
     
     
       18. The process according to claim 1, wherein the weight ratio of molybdenum oxide to vanadium oxide is 2:1 to 8:1.